The concept of optical beam self-trapping in pyroelectric photorefractive medium is presented. We show that the temperature controlled spontaneous polarisation of ferroelectric crystals produces an optical nonlinearity that can lead to formation of 2-D spatial soliton named pyroliton. Experimental demonstrations performed in lithium niobate crystals illustrate that efficient self-trapping occurs either for ordinary or extraordinary polarisation under moderate temperature increase. For instance, a 15µm diameter pyroliton can be formed with a 10 degree temperature raise.

Nonlinear periodically poled ridge LiNbO ₃ waveguides have been fabricated on silicon substrates. Components are carved with only the use of a precision dicing machine without the need for grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 204%/W in a 15 mm long device. The influence of the geometrical non uniformities of waveguides due to fabrication processes is asserted. Characteristics of the components are studied; notably their robustness and tunability versus temperature.

We demonstrated an experimental observation of self-trapping and self-deflection of a two-dimensional optical beam by the photorefractive effect at telecommunication wavelengths under an applied dc field. Self-trapping is effective for an intensity range related to the intensity-temperature resonance known for two-wave mixing in InP:Fe. The photorefractive index change giving rise to the trapping is measured at 10−4, while the photorefractive space-charge field is measured at about 50 kV/cm, ten times higher than the applied field. We show experimentally that this index change creates a waveguide that can be used to guide a second beam at 1.55 μm.

We report the observation of large self-deflection of 2-D bright photorefractive solitons in ${\mathrm{LiNbO}}_3$ crystal under a dc applied field. Beam deflection as large as $300\mu \mathrm{m}$ after a 7 mm propagation distance is reported, leading to formation of curved 2-D waveguides. We attribute this large deflection to the low level of impurity acceptors present in the samples, as confirmed by numerical results from a time-dependent photorefractive model.

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Surface-wave solitons, induced by the pyroelectric effect, are formed at the interface between a photorefractive ferroelectric medium and a linear medium. These optical solitons are trapped in both transverse dimensions and are efficiently attracted to the interface. The asymmetric shape of the nonlinear index change formed under the charge saturation regime is responsible for the surface-wave solitons’ formation. Experimental demonstrations are performed in a lithium niobate sample with moderate temperature change. The phenomenon is successfully explained through numerical simulations.